CVE-2019-19919
Arbitrary Code Execution in handlebars
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
9.8
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
CVE-2019-19919- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-1321
- Updated
- 2026-11-02
CVE List No score
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
CVE-2019-19919- Updated
- 2026-11-02
EUVDEUVD-2019-0803 No score
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
EUVD-2019-0803- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-2cf5-4w76-r9qv
7.3
Arbitrary Code Execution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.2 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).
The following template can be used to demonstrate the vulnerability:
{{#with split as |a|}}
{{pop (push "alert('Vulnerable Handlebars JS');")}}
{{#with (concat (lookup join (slice 0 1)))}}
{{#each (slice 2 3)}}
{{#with (apply 0 a)}}
{{.}}
{{/with}}
{{/each}}
{{/with}}
{{/with}}
{{/with}}```
## Recommendation
Upgrade to version 3.0.8, 4.5.2 or later.
- Record
GHSA-2cf5-4w76-r9qv- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-94
- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-q42p-pg8m-cqh6
7.3
Prototype Pollution in handlebars
Versions of handlebars prior to 4.0.14 are vulnerable to Prototype Pollution. Templates may alter an Objects' prototype, thus allowing an attacker to execute arbitrary code on the server.
Recommendation
For handlebars 4.1.x upgrade to 4.1.2 or later. For handlebars 4.0.x upgrade to 4.0.14 or later.
- Record
GHSA-q42p-pg8m-cqh6- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-471
- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-w457-6q6x-cgp9
9.8
Prototype Pollution in handlebars
Versions of handlebars prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects' __proto__ and __defineGetter__ properties, which may allow an attacker to execute arbitrary code through crafted payloads.
Recommendation
Upgrade to version 3.0.8, 4.3.0 or later.
- Record
GHSA-w457-6q6x-cgp9- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-74, CWE-1321
- Updated
- 2026-11-02
Show 22 moreShow less
GitHub AdvisoriesGHSA-g9r4-xpmj-mj65 No score
Prototype Pollution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.
Recommendation
Upgrade to version 3.0.8, 4.5.3 or later.
- Record
GHSA-g9r4-xpmj-mj65- Weakness
- CWE-1321
- Updated
- 2026-11-02
GitHub AdvisoriesGHSA-q2c6-c6pm-g3gh No score
Arbitrary Code Execution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).
Recommendation
Upgrade to version 3.0.8, 4.5.3 or later.
- Record
GHSA-q2c6-c6pm-g3gh- Updated
- 2026-11-02
OSV
9.8
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
CVE-2019-19919- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVDEBIAN-CVE-2019-19919
9.8
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
DEBIAN-CVE-2019-19919- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-2cf5-4w76-r9qv
7.3
Arbitrary Code Execution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.2 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).
The following template can be used to demonstrate the vulnerability:
{{#with split as |a|}}
{{pop (push "alert('Vulnerable Handlebars JS');")}}
{{#with (concat (lookup join (slice 0 1)))}}
{{#each (slice 2 3)}}
{{#with (apply 0 a)}}
{{.}}
{{/with}}
{{/each}}
{{/with}}
{{/with}}
{{/with}}```
## Recommendation
Upgrade to version 3.0.8, 4.5.2 or later.
- Record
GHSA-2cf5-4w76-r9qv- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:C/C:L/I:H/A:L - Weakness
- CWE-94
- Updated
- 2026-11-02
OSVGHSA-q42p-pg8m-cqh6
7.3
Prototype Pollution in handlebars
Versions of handlebars prior to 4.0.14 are vulnerable to Prototype Pollution. Templates may alter an Objects' prototype, thus allowing an attacker to execute arbitrary code on the server.
Recommendation
For handlebars 4.1.x upgrade to 4.1.2 or later. For handlebars 4.0.x upgrade to 4.0.14 or later.
- Record
GHSA-q42p-pg8m-cqh6- CVSS 3.1
- 7.3 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L - Weakness
- CWE-471
- Updated
- 2026-11-02
OSVGHSA-w457-6q6x-cgp9
9.8
Prototype Pollution in handlebars
Versions of handlebars prior to 3.0.8 or 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Objects' __proto__ and __defineGetter__ properties, which may allow an attacker to execute arbitrary code through crafted payloads.
Recommendation
Upgrade to version 3.0.8, 4.3.0 or later.
- Record
GHSA-w457-6q6x-cgp9- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-1321, CWE-74
- Updated
- 2026-11-02
OSVUBUNTU-CVE-2019-19919
9.8
Versions of handlebars prior to 4.3.0 are vulnerable to Prototype Pollution leading to Remote Code Execution. Templates may alter an Object's proto and defineGetter properties, which may allow an attacker to execute arbitrary code through crafted payloads.
- Record
UBUNTU-CVE-2019-19919- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVCLSA-2026-1773101681 No score
TuxCare security update for handlebars (9 CVEs)
TuxCare rebuilt handlebars to address 9 CVEs. Fixed in 3.0.3-tuxcare.1.
- Record
CLSA-2026-1773101681- Updated
- 2026-11-02
OSVCLSA-2026-1774743817 No score
TuxCare security update for handlebars (1 CVE)
TuxCare rebuilt handlebars to address 1 CVE. Fixed in 1.3.0-tuxcare.1.
- Record
CLSA-2026-1774743817- Updated
- 2026-11-02
OSVCLSA-2026-1774743830 No score
TuxCare security update for handlebars (3 CVEs)
TuxCare rebuilt handlebars to address 3 CVEs. Fixed in 1.0.12-tuxcare.2.
- Record
CLSA-2026-1774743830- Updated
- 2026-11-02
OSVCLSA-2026-1774743831 No score
TuxCare security update for handlebars (2 CVEs)
TuxCare rebuilt handlebars to address 2 CVEs. Fixed in 1.3.0-tuxcare.2.
- Record
CLSA-2026-1774743831- Updated
- 2026-11-02
OSVCLSA-2026-1774743832 No score
TuxCare security update for handlebars (2 CVEs)
TuxCare rebuilt handlebars to address 2 CVEs. Fixed in 2.0.0-tuxcare.2.
- Record
CLSA-2026-1774743832- Updated
- 2026-11-02
OSVCLSA-2026-1776991069 No score
TuxCare security update for handlebars (9 CVEs)
TuxCare rebuilt handlebars to address 9 CVEs. Fixed in 4.7.9-tuxcare.1.
- Record
CLSA-2026-1776991069- Updated
- 2026-11-02
OSVCLSA-2026-1786731948 No score
TuxCare security update for dompurify (34 CVEs)
TuxCare rebuilt dompurify to address 34 CVEs. Fixed in 3.0.3-tuxcare.1.
- Record
CLSA-2026-1786731948- Updated
- 2026-11-02
OSVGHSA-g9r4-xpmj-mj65 No score
Prototype Pollution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to prototype pollution. It is possible to add or modify properties to the Object prototype through a malicious template. This may allow attackers to crash the application or execute Arbitrary Code in specific conditions.
Recommendation
Upgrade to version 3.0.8, 4.5.3 or later.
- Record
GHSA-g9r4-xpmj-mj65- Weakness
- CWE-1321
- Updated
- 2026-11-02
OSVGHSA-q2c6-c6pm-g3gh No score
Arbitrary Code Execution in handlebars
Versions of handlebars prior to 3.0.8 or 4.5.3 are vulnerable to Arbitrary Code Execution. The package's lookup helper fails to properly validate templates, allowing attackers to submit templates that execute arbitrary JavaScript in the system. It is due to an incomplete fix for a previous issue. This vulnerability can be used to run arbitrary code in a server processing Handlebars templates or on a victim's browser (effectively serving as Cross-Site Scripting).
Recommendation
Upgrade to version 3.0.8, 4.5.3 or later.
- Record
GHSA-q2c6-c6pm-g3gh- Updated
- 2026-11-02
OSVROOT-APP-NPM-CVE-2019-19919 No score
CVE-2019-19919 in handlebars - Patched by Root
Root has patched CVE-2019-19919 in the handlebars package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-CVE-2019-19919- Updated
- 2026-11-02
OSVROOT-APP-NPM-GHSA-2cf5-4w76-r9qv No score
GHSA-2cf5-4w76-r9qv in handlebars - Patched by Root
Root has patched GHSA-2cf5-4w76-r9qv in the handlebars package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-GHSA-2cf5-4w76-r9qv- Updated
- 2026-11-02
OSVROOT-APP-NPM-GHSA-g9r4-xpmj-mj65 No score
GHSA-g9r4-xpmj-mj65 in handlebars - Patched by Root
Root has patched GHSA-g9r4-xpmj-mj65 in the handlebars package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-GHSA-g9r4-xpmj-mj65- Updated
- 2026-11-02
OSVROOT-APP-NPM-GHSA-q2c6-c6pm-g3gh No score
GHSA-q2c6-c6pm-g3gh in handlebars - Patched by Root
Root has patched GHSA-q2c6-c6pm-g3gh in the handlebars package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-GHSA-q2c6-c6pm-g3gh- Updated
- 2026-11-02
OSVROOT-APP-NPM-GHSA-q42p-pg8m-cqh6 No score
GHSA-q42p-pg8m-cqh6 in handlebars - Patched by Root
Root has patched GHSA-q42p-pg8m-cqh6 in the handlebars package for Root:npm. Multiple fixed versions available.
- Record
ROOT-APP-NPM-GHSA-q42p-pg8m-cqh6- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
handlebarsnpm |
before 3.0.8 | 3.0.8 |
handlebarsnpm |
4.0.0 up to 4.5.2 | 4.5.2 |
handlebarsnpm |
4.0.0 up to 4.5.3 | 4.5.3 |
handlebarsnpm |
4.1.0 up to 4.1.2 | 4.1.2 |
handlebarsnpm |
4.0.0 up to 4.0.14 | 4.0.14 |
handlebarsnpm |
before 3.0.7 | 3.0.7 |
handlebarsnpm |
4.0.0 up to 4.3.0 | 4.3.0 |
bootstrap-wysihtml5-railsRubyGems |
0.3.3.5 to 0.3.3.8 | None known |
handlebarsTuxCare:npm From an advisory covering 5 CVEs |
3.0.3-tuxcare.0 up to 3.0.3-tuxcare.1, plus listed versions 3.0.3 |
3.0.3-tuxcare.1 |
handlebarsTuxCare:npm |
1.3.0-tuxcare.0 up to 1.3.0-tuxcare.1, plus listed versions 1.3.0 |
1.3.0-tuxcare.1 |
Show 13 moreShow less
| Package | Affected | Fixed |
|---|---|---|
handlebarsTuxCare:npm |
1.0.12-tuxcare.0 up to 1.0.12-tuxcare.2, plus listed versions 1.0.121.0.12-tuxcare.1 |
1.0.12-tuxcare.2 |
handlebarsTuxCare:npm From an advisory covering 2 CVEs |
1.3.0-tuxcare.0 up to 1.3.0-tuxcare.2, plus listed versions 1.3.01.3.0-tuxcare.1 |
1.3.0-tuxcare.2 |
handlebarsTuxCare:npm From an advisory covering 2 CVEs |
2.0.0-tuxcare.0 up to 2.0.0-tuxcare.2, plus listed versions 2.0.02.0.0-tuxcare.1 |
2.0.0-tuxcare.2 |
handlebarsTuxCare:npm From an advisory covering 5 CVEs |
4.7.9-tuxcare.0 up to 4.7.9-tuxcare.1, plus listed versions 4.7.9 |
4.7.9-tuxcare.1 |
node-handlebarsDebian:12 |
before 3:4.5.3-1 | 3:4.5.3-1 |
node-handlebarsDebian:13 |
before 3:4.5.3-1 | 3:4.5.3-1 |
node-handlebarsDebian:14 |
before 3:4.5.3-1 | 3:4.5.3-1 |
bootstrap-wysihtml5-railsRubyGems |
0.3.3.5 to 0.3.3.8, plus listed versions 0.3.3.60.3.3.7 |
None known |
handlebarsRoot:npm |
before 3.0.7-aikido.3 | 3.0.7-aikido.33.0.3-aikido.23.0.8-aikido.13.0.8-aikido.2 |
@rootio/handlebarsRoot:npm |
before 3.0.7-root.io.3 | 3.0.7-root.io.33.0.3-root.io.23.0.8-root.io.13.0.8-root.io.2 |
handlebarsRoot:npm |
before 3.0.3-aikido.2 | 3.0.3-aikido.23.0.7-aikido.13.0.7-aikido.23.0.7-aikido.3 |
@rootio/handlebarsRoot:npm |
before 3.0.3-root.io.2 | 3.0.3-root.io.23.0.7-root.io.13.0.7-root.io.23.0.7-root.io.3 |
node-handlebarsUbuntu:18.04:LTS |
All versions, plus listed versions 3:4.0.10-5 |
None known |
Public exploits
Links only. Every CVE stores no exploit code.
| Source | Link | Date |
|---|---|---|
| PoC in GitHub | fazilbaig1/CVE-2019-19919 | 2024-10-19 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected | ||
| facts | ||
| affected | ||
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV, PoC in GitHub |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2019-19919 is a critical vulnerability (CVSS 9.8) in Handlebars.js Project Handlebars.js, published June 5, 2019. Public exploit code exists. EPSS puts the chance of exploitation in the next 30 days at 7.07%, the 94th percentile. Fixed in handlebars 3.0.8.
References
npmjs.com/advisories/1164
tenable.com/security/tns-2021-14
npmjs.com/advisories/1316
github.com/advisories/GHSA-2cf5-4w76-r9qv
npmjs.com/advisories/1325
github.com/advisories/GHSA-g9r4-xpmj-mj65
Show 24 moreShow less
npmjs.com/advisories/1324
github.com/advisories/GHSA-q2c6-c6pm-g3gh
github.com/handlebars-lang/handlebars.js/issues/1495
github.com/handlebars-lang/handlebars.js/commit/7372d4e9dffc9d70c09671aa28b9392a1577fd86
snyk.io/vuln/SNYK-JS-HANDLEBARS-173692
npmjs.com/advisories/755
github.com/handlebars-lang/handlebars.js/commit/0d6d8c335ad81bad1b672fc56b6a44f6aa472dac
github.com/handlebars-lang/handlebars.js/commit/85c8783b34fc6d36145d8b53885ad0b9e3c3f9c4
github.com/handlebars-lang/handlebars.js/commit/cd38583216dce3252831916323202749431c773e
github.com/advisories/GHSA-q42p-pg8m-cqh6
nvd.nist.gov/vuln/detail/CVE-2019-19919
github.com/wycats/handlebars.js/issues/1558
github.com/wycats/handlebars.js/commit/2078c727c627f25d4a149962f05c1e069beb18bc
cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2019-19919
github.com/handlebars-lang/handlebars.js/commit/156061eb7707575293613d7fdf90e2bdaac029ee
github.com/handlebars-lang/handlebars.js/commit/90ad8d97ad2933852fb83fcc054699dc99e094db
github.com/Nerian/bootstrap-wysihtml5-rails/blob/master/vendor/assets/javascripts/bootstrap-wysihtml5/handlebars.runtime.min.js
github.com/Nerian/bootstrap-wysihtml5-rails/tree/master/vendor/assets/javascripts/bootstrap-wysihtml5
github.com/rubysec/ruby-advisory-db/blob/master/gems/bootstrap-wysihtml5-rails/CVE-2019-19919.yml
github.com/advisories/GHSA-w457-6q6x-cgp9
security-tracker.debian.org/tracker/CVE-2019-19919
github.com/wycats/handlebars.js
ubuntu.com/security/CVE-2019-19919
cve.org/CVERecord?id=CVE-2019-19919